Electron Paramagnetic Resonance (EPR Oxygen Images (EPROI) have been shown to provide quantitative localized PO2 images of animal tumors including several in syngeneic mice, and in rats, and rabbits. The oxygen broadening of narrow EPR spectral lines report the PO2 with 1-3 torr resolution in each 1mm3 image voxeL This work has shown i) the first co-localized correlation between an oxygen image and a point oxygen measurement technique (Oxylite) 2) independent, statistically significant sharpening of the 50% tumor control dose with the addition of the information provided by the fraction of EPROI voxels less than io torr (HFio) 3) co-registration of pimonidazole images nth EPROI PO2 and 4) significant spatial correlation of VEOF and EPROI based HEw. We propose the following specific aims for the given cycle: i) Determining the relation between the localized oxygen information from the EPROI and pimonidazole retention and induction of hypoxia proteins, 2) Treatment of murine tumors to TCDSO after oxygen images and determining the predictive effectiveness of the HFio and other EPROT tumor statistics.